Lock for an instant release switch



June 16, 1959 sLAvlN v 2,891,135

LOCK FOR AN INSTANT RELEASE SWITCH` Filed Sept. 25,"1957 70 i7 2O 141-* 13 (5a/dumb@ MMI/124 United States Patent O LOCK FOR AN INSTANT RELEASE SWITCH Edwin Slavin, Deerfield, Ill.

Application September 25, 1957, Serial No. 686,111

8 Claims. (Cl. 20G-172) This invention relates to a lock for an instant release switch and is particularly concerned with means for locking the switch of a portable power saw or similar tool in closed position when the saw is mounted on a work bench or table.

Safety regulations generally require that portable power saws and similar tools be provided with an instant release switch that may be held in closed position only while iinger pressure against the switch is maintained. Immediately upon release of the finger pressure from the switch, spring pressure automatically moves it to open position. This type of switch serves satisfactorily as long as the tool is held in the operators hand and is being used as a portable tool. However, if the tool is mounted on a work bench or table, the instant release switch is a nuisance and interferes seriously with etlicient use of the particular tool,

In accordance with my invention, I have provided a very simple, eicient lock that may be detachably secured to the tool when the tool is mounted on a work bench. The lock comprises a flat angular bar adapted to be moved pivotally into holding engagement with the switch of a power tool and held against accidental release by the spring action of the switch. The lock bar is pivotally secured to the tool adjacent the center of the bar to leave one end of the bar to serve as a handle.

The other end of the bar is shaped to abut an edge of the motor housing, and the bar is slidable longitudinally between a locked position and a release position. Although the lock bar may be readily slid from its switch holding or locked position to its release position, it is firmly held in the locked position by the same spring action which tends to release the switch, and cannot be moved accidentally from one position to the other. The lock bar may be readily removed from the tool, if desired, when the tool is to be used as a portable tool, and easily reapplied to the tool when the tool is mounted on a work bench or table.

The structure by means of which the above mentioned and other advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawing, showing a preferred illustrative embodiment of the invention, in which:

Figure l is a side elevational view showing the power saw mounted on a work table, with portions broken away to show the lock structure;

Fig. 2 is a fragmentary side elevational view, showing the lock bar held in locked position;

Fig. 3 is a fragmentary perspective view, showing the lock bar in locked position; and

Fig. 4 is a fragmentary cross sectional view, taken along the line 4 4 of Fig. 2.

In the drawing, the reference numeral 2 indicates a work table in which a portable power tool, such as, for example, a saw 3, is mounted. The work table comprises a flat table top 4 and a supporting structure 5. The supporting structure may comprise a plurality of vertical uprights, but I prefer to provide closed walls.

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One end wall is provided with an opening 6 to allow access to the mechanism mounted on the underside of the table top.

The table top has a slotted longitudinally-extending opening (not shown) through which a portion of the saw blade 7 projects. A retractible guard 8 extends around the projecting portion of the saw blade. As the work is advanced past the cutting edge of the saw blade, it presses against the spring action of the guard 8, to move the guard out of the way of the work.

The motor is encased in a housing 9 which is provided with an integral tubular handle 10. The handle 10 may be separate, but must then be rigidly secured to the housing to allow the saw to be handled as a portable tool, when desired. The intermediate portion of the tubular handle 10 is spaced from the housing 9 to provide a hand hole to facilitate grasping the saw. 'Ihe motor may be connected to any suitable electric source by means of a wire cord 11 which extends from the motor through the opening 6.

The operation of the motor is controlled by a switch 12 pivotally mounted on a pin 13 extending transversely of the tubular handle 10, The upper end of the switch projects through an opening 14 in the inner wall of the tubular handle facing the motor housing, A coiled compression spring 15 seated on a tit 16 projecting from the back side of the switch has its other end bearing against the opposite wall of the tubular handle 10 and exerts a constant force urging the switch 12 outwardly into its open position. Finger pressure applied against the switch presses it into closed position, but as soon as the finger pressure is released, the spring presses the switch into open position again.

A flat angular lock bar 17 is provided with a centrally disposed slot 19 extending substantially longitudinally of the bar. 'Ihe lock bar is detachably secured to one side of the handle 10 by means of a screw 18 which extends through the slot 19 and is threaded into the handle 10. A washer 20 is provided between the head of the screw 18 and the outer surface of the lock bar. The screw permits longitudinal movement of the bar within the limits of the length of the slot and also permits pivotal movement of the bar. A portion of the bar is bent at right angles to form a lip 21 intermediate the slot 19 and the end 22 of the bar. The end 22 is preferably angularly shaped, but may be square or rounded, if desired.

As shown in Fig. 2, the housing 9 is preferably approximately square in transverse section, to provide angular corners 23, one of which serves as an abutment adapted to be engaged by the end 22 of the lock bar, when the lock bar is in locking position. The housing may be of any suitable shape, if an abutment is provided to engage the end 22 of the lock bar, and the lock bar may be moved to permit the end 22 to clear the abutment. If the housing is cylindrical, the lock bar must be dimensioned so that when the end of the slot 19 remote from the housing abuts the screw 18, and the lock bar is moved pivotally about the screw, the circle defined by the end of the lock bar intersects the perimeter of the housing. In this case the portion of the peripheral surface of the housing which is engaged by the end 22 of the lock bar serves as 'an abutment.

The lip 21 extends transversely in front of the spring pressed switch 12 and may be moved into engagement with its outer edge, Normally the lock bar swings freely on the screw 18 and the switch 12 may be closed by iinger pressure and opened by removing the finger pressure from the switch. In order to lock the switch in closed position, the bar 17 is pulled away from the motor housing 9 to move the angular end 22 clear of the angular corner 23 of the motor housing 9. 'Ihe bar 17 is then moved pivotally so that the end 22 of the bar passes.

the adjacent corner 23 of the motor housing. This piv- Otal movement of the bar causes the lip 2li to engage the switch 12 and close it against the action of the spring 15.

As soon as the bar i7 is released, the spring l5 moves the lip 2l outwardly until the end of the slot 19 remote from the motor housing abuts the screw 18 with the end 22 of the bar in engagement with the motor housing adjacent the corner 23. When the lock bar is in locked position, the angular corner 23 prevents it from moving pivotally in one direction. The spring l prevents the lock bar from moving pivotally in the opposite direction, and also prevents it from accidentally moving longitudinally. With the lock bar held against accidental movement in any direction, the lip 2l holds the switch in its closed position.

In order to move the switch to its open position, the bar is manually moved longitudinally against the action of the spring 15, and then moved pivotally until the end 22 passes the corner 23 of the motor housing. The pivotal movement of the bar in this direction moves the lip 21 away from the switch 12, and the spring l5 immediately moves the switch outwardly to its open position.

Although the bar t7 is securely held against accidental displacement in the position shown in Figs. 2 and 3, it requires little force to pull the bar against the action of the spring and then move it pivotally to position the end 22 on the other side of the adjacent corner 23 of the motor housing, to release the switch. When the tool is to be used as a portable tool, the lock har may be readily removed by unscrewing the screw 18.

While I have described a preferred embodiment of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather rather than restrictive, as many details of the structure may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction described.

I claim:

1. In combination with a power tool having a motor housing, an abutment on said housing, a switch mounted in spaced relationship to said motor housing and a spring urging said switch into open position, a lock bar pivotally mounted on said tool in spaced relationship to said housing, said lock bar having a slot extending substantially longitudinally thereof to permit sliding movement of said lock bar relative to said housing to cause one end of said lock bar to engage or to clear said abutment when said lock bar is moved pivotally, and means for holding said lock bar in engagement with said abutment.

2. A power tool comprising a housing, a handle extending from said housing, a switch mounted on said handle, a spring bearing against said switch to urge it outwardly into open position, a lock bar pivotally mounted on said handle and slidable relative thereto to engage or to clear said housing when the lock bar is moved pivotally relative to said handle, said switch engaging said lock bar when said lock bar is in engagement with said housing, said spring exerting force against said switch to hold said lock bar against accidental disengagement from said housing.

3. A power tool comprising a motor, a switch for controlling the operation of said motor, a spring urging said switch to open position, an abutment in spaced relationship to said switch, and a lock bar engageable with said abutment and said switch to hold said switch in closed position, said switch urging said lock bar against said abutment to hold said lock bar against accidental displacement relative to said abutment or switch.

L A power tool comprising a motor, a housing encasing said motor, a switch for controlling the operation of said motor, said switch being mounted in spaced relationship to said housing, a spring urging said switch to open position, and a lock bar engageable with said switch and said housing to hold said switch in closed position, said switch urging said lock bar against said housing to prevent accidental displacement of said lock bar relative to said housing or switch to thereby lock said switch in closed position.

5. A power tool comprising a motor, a housing encasing said motor, a handle extending from said housing, a switch mounted on said handle, a spring urging said switch to open position, and a lock bar pivotally mounted on said handle, said lock bar being engageable with said housing and said switch to close said switch against the action of said spring, said switch urging said lock bar into engagement with said housing to prevent accidental displacement of said lock bar from said switch closing position.

6. A power tool comprising a motor, a housing encasing said motor, a handle extending from said housing, a switch mounted on said handle, a spring urging said switch to open position, a lock bar pivotally mounted .on said handle, and engageable simultaneously with said housing and said switch, said switch holding said lock bar against accidental displacement from interengagement with said housing and switch in said position, said lock bar being manually slidable against the action of said switch and spring to release it from engagement with said housing and thereby cause movement of said switch to open position.

7. A power tool comprising a motor, a housing e11- casing said motor, a handle extending from said housing, a switch mounted on said handle, a flat angular lock bar having a substantially longitudinal slot therein, fastening means extending through said slot and secured to said handle to hold said lock bar in pivotal and slidable relationship to said handle, said lock bar having one end engageable with said housing, and a lip extending from said lock bar and adapted to press said switch to closed position against the action of said spring when said one end of the lock bar is in engagement with said housing, said spring cooperating with said switch and said housing to hold said lock bar against accidental displacement from said switch closing position.

8. A power tool comprising a housing having an angular corner, a handle extending from said housing, a switch mounted on said handle, a spring urging said switch to open position, a lock bar pivotally mounted on said handle, said lock bar being slidable between two extreme positons, said lock bar having one end engageable with said angularcorner when moved pivotally in one of said positions, said one end being movable past said corner when said lock bar is moved pivotally in said second position, and a lip extending from said lock bar into engagement with said switch to hold it closed when said lock bar is in said first mentioned position with its end in engagement with said housing on one side of said angular corner.

References Cited in the tile of this patent UNITED STATES PATENTS 1,929,662 Wappat Oct. l0, 1933 

